This invention relates to a cylinder head gasket and more particularly to an improved sealing arrangement for the seal around the cylinder bore of a reciprocating machine such as an internal combustion engine.
As is well known, most engines are comprised of a cylinder block having one or more cylinder bores and a cylinder head which is affixed to the cylinder block and which closes the cylinder bore. There is conventionally positioned some form of head gasket between the cylinder head and the cylinder block and around the cylinder bores for effecting a seal.
A type of cylinder head gasket frequently utilized for this purpose has certain disadvantages, which may be best understood by reference to FIG. 1 which shows a conventional prior art type of construction of this nature. Only a portion of the cylinder block is shown, but this is believed to be all that is necessary for those skilled in the art to understand the problems with the prior art type of construction.
In this construction, a cylinder block, indicated generally by the reference numeral 11, has a pair of liners 12 inserted therein and which form respective cylinder bores 13. The cylinder block 11 has an upwardly extending portion 14 that defines a shoulder into which cylindrical projections 15 of the cylinder liner extend. The cylinder liners 12 have recesses 16 formed above these projections 15, and these recesses 16 along with the cylinder block portion 14 form a recess in which cylinder head gaskets 17 are positioned.
In the illustrated embodiment, the cylinder head gaskets 17 are formed as annular members from a suitable sealing material. That is, there is one cylinder head sealing gasket 17 for each cylinder bore 13. In their uncompressed state, the cylinder head gaskets 17 extend above the upper deck of the cylinder block and cylinder liners by a distance indicated at .DELTA.t. When the cylinder head is affixed to the cylinder block 11, there will be a downward force, indicated by the arrow P, exerted on the gasket 17 so as to compress them in the grooves formed by the recesses 16 and the ledge 14 of the cylinder block 11.
The material employed for the cylinder head gasket 17 is, like most material, substantially incompressible. Therefore, if the volume of the gasket 17 is greater than the volume of the area between the groove 16 and the cylinder wall portion 14, the gasket 17 when compressed will place a force on the upper end of the cylinder liners 12, causing them to deflect, as shown in the broken-line portion of this figure. This distortion, even though it may be quite small, nevertheless gives rise to problems which should be obvious to those skilled in the art.
It is, therefore, a principal object of this invention to provide an improved cylinder head gasket arrangement which will provide effective sealing but which will not cause any side forces on the member in which it is received which would cause that member to deflect.
It is a further object of this invention to provide an improved cylinder head gasket arrangement for an engine or other reciprocating type of machine.